diff --git a/extensions/qa-lab/src/providers/mock-openai/server.test.ts b/extensions/qa-lab/src/providers/mock-openai/server.test.ts
index f5fe5998105..90566f7dc31 100644
--- a/extensions/qa-lab/src/providers/mock-openai/server.test.ts
+++ b/extensions/qa-lab/src/providers/mock-openai/server.test.ts
@@ -834,7 +834,9 @@ describe("qa mock openai server", () => {
       }),
     });
     expect(memory.status).toBe(200);
-    expect(await memory.text()).toContain('"name":"memory_search"');
+    const memoryText = await memory.text();
+    expect(memoryText).toContain('"name":"memory_search"');
+    expect(memoryText).toContain('\\"corpus\\":\\"sessions\\"');
 
     const memoryFollowup = await fetch(`${server.baseUrl}/v1/responses`, {
       method: "POST",
diff --git a/extensions/qa-lab/src/providers/mock-openai/server.ts b/extensions/qa-lab/src/providers/mock-openai/server.ts
index f7dfa6c69fa..2224f8177c5 100644
--- a/extensions/qa-lab/src/providers/mock-openai/server.ts
+++ b/extensions/qa-lab/src/providers/mock-openai/server.ts
@@ -1373,6 +1373,7 @@ async function buildResponsesPayload(
       return buildToolCallEventsWithArgs("memory_search", {
         query: "current Project Nebula codename ORBIT-10",
         maxResults: 3,
+        corpus: "sessions",
       });
     }
     const results = Array.isArray(toolJson?.results)
diff --git a/qa/scenarios/memory/session-memory-ranking.md b/qa/scenarios/memory/session-memory-ranking.md
index d3101c0fa8f..acbbe85870a 100644
--- a/qa/scenarios/memory/session-memory-ranking.md
+++ b/qa/scenarios/memory/session-memory-ranking.md
@@ -127,6 +127,18 @@ steps:
                 - ref: transcriptPath
                 - expr: "[JSON.stringify({ type: 'session', id: config.transcriptId, timestamp: new Date(now - 120000).toISOString() }), JSON.stringify({ type: 'message', message: { role: 'user', timestamp: new Date(now - 90000).toISOString(), content: [{ type: 'text', text: config.transcriptQuestion }] } }), JSON.stringify({ type: 'message', message: { role: 'assistant', timestamp: new Date(now - 60000).toISOString(), content: [{ type: 'text', text: config.transcriptAnswer }] } })].join('\\n') + '\\n'"
                 - utf8
+            - call: readRawQaSessionStore
+              saveAs: sessionStore
+              args:
+                - ref: env
+            - set: sessionStorePath
+              value:
+                expr: "path.join(env.gateway.tempRoot, 'state', 'agents', 'qa', 'sessions', 'sessions.json')"
+            - call: fs.writeFile
+              args:
+                - ref: sessionStorePath
+                - expr: "JSON.stringify({ ...sessionStore, ['agent:qa:seed-session-memory-ranking']: { sessionId: config.transcriptId, updatedAt: now, sessionFile: transcriptPath, origin: { label: 'QA seeded session memory ranking transcript' } } }, null, 2)"
+                - utf8
             - call: forceMemoryIndex
               args:
                 - env: